Mentions in LinkedIn comments do not work via API

Question

When trying to mention a user, an error is returned: API endpoint docs

What I do:

POST https://api.linkedin.com/rest/socialActions/urn%3Ali%3Ashare%3A%7BshareId%7D/comments

Request body:

{
    "actor": "urn:li:organization:{actorId}",
    "object": "urn:li:share:{shareId}",
    "message": {
        "attributes": [
            {
                "length": 14,
                "start": 0,
                "value": {
                    "com.linkedin.adsexternalapi.social.PersonAttributedEntity": {
                        "person": "urn:li:person:{personId}"
                    }
                }
            }
        ],
        "text": "Mentioned user test message!"
    }
}

Response:

{
    "message": "ERROR :: /message/attributes/0/value/com.linkedin.adsexternalapi.social.PersonAttributedEntity :: unrecognized field found but not allowed\nERROR :: /message/attributes/0/value :: \"com.linkedin.adsexternalapi.social.PersonAttributedEntity\" is not a member type of union",
    "status": 422
}

The request is made by analogy with what is indicated in the example.

Answer 1

The documentation appears to be wrong...

I was able to get comment mentions working by using:

{
    "actor": "urn:li:organization:{actorId}",
    "object": "urn:li:share:{shareId}",
    "message": {
        "attributes": [
            {
                "length": 14,
                "start": 0,
                "value": {
                    "com.linkedin.common.MemberAttributedEntity": {
                        "person": "urn:li:person:{personId}"
                    }
                }
            }
        ],
        "text": "Mentioned user test message!"
    }
}

I searched for some older docs and that solved the issue.

Value attributes are com.linkedin.common.CompanyAttributedEntity and com.linkedin.common.MemberAttributedEntity

More info: https://learn.microsoft.com/en-us/linkedin/compliance/integrations/shares/ugc-post-api?tabs=http#mentions-in-ugc-posts

Here's my entire funtion:

export const createComment = async (
  accessToken: string,
  postUrn: string,
  commentParams: CommentMutation,
): Promise<string | undefined> => {
  return (
    await axios.post(
      `https://api.linkedin.com/v2/socialActions/${postUrn}/comments`,
      {
        ...commentParams,
      },
      {
        headers: {
          Authorization: `Bearer ${accessToken}`,
          "Content-Type": "application/json",
        },
      },
    )
  ).data;
};